title: Comprehensive mutation analysis of PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1 genes is suggestive of a non- neoplastic nature of phenytoin induced gingival overgrowth.
abstract: BACKGROUND
  Dilantin sodium (phenytoin) is an antiepileptic drug, which is routinely used to control generalized tonic clonic seizure and partial seizure episodes. A few case reports of oral squamous cell carcinomas arising from regions of phenytoin induced gingival overgrowth (GO), and overexpression of mitogenic factors and p53 have presented this condition as a pathology with potential to transform into malignancy. We recently investigated the genetic status of p53 and H-ras, which are known to be frequently mutated in Indian oral carcinomas in GO tissues and found them to only contain wild type sequences, which suggested a non-neoplastic nature of phenytoin induced GO. However, besides p53 and H-ras, other oncogenes and tumor suppressors such as PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1, are frequently altered in oral squamous cell carcinoma, and hence are required to be analyzed in phenytoin induced GO tissues to be affirmative of its non-neoplastic nature.
  
  
  METHODS
  100ng of chromosomal DNA isolated from twenty gingival overgrowth tissues were amplified with primers for exons 9 and 20 of PIK3CA, exons 1α, 1β and 2 of p16INK4a and p14ARF, and exon 2 of p21Waf1/Cip1, in independent reactions. PCR amplicons were subsequently gel purified and eluted products were sequenced.
  
  
  RESULTS
  Sequencing analysis of the twenty samples of phenytoin induced gingival growth showed no mutations in the analyzed exons of PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1.
  
  
  CONCLUSIONS
  The present data indicate that the mutational alterations of genes, PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1 that are frequently mutated in oral squamous cell carcinomas are rare in phenytoin induced gingival growth. Thus the findings provide further evidence that phenytoin induced gingival overgrowth as a non-neoplastic lesion, which may be considered as clinically significant given the fact that the epileptic patients are routinely administered with phenytoin for the rest of their lives to control seizure episodes.
authors.affiliation: Department of Prosthodontia, Sree Balaji Dental College and Hospital, Bharath University, Chennai, India.
authors.forename: Bhuminathan
authors.initials: B
authors.lastname: Swamikannu
authors.forename: Kishore S
authors.initials: KS
authors.lastname: Kumar
authors.forename: Raghavendra S
authors.initials: RS
authors.lastname: Jayesh
authors.forename: Senthilnathan
authors.initials: S
authors.lastname: Rajendran
authors.forename: Rajendran Shanmugam
authors.initials: RS
authors.lastname: Muthupalani
authors.forename: Arvind
authors.initials: A
authors.lastname: Ramanathan
mesh_terms: D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced; D058534:Class I Phosphatidylinositol 3-Kinases; D003430:Cross-Sectional Studies; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics*; D004252:DNA Mutational Analysis; D019214:Gingival Overgrowth / Q000235:genetics*; D006801:Humans; D009062:Mouth Neoplasms / Q000139:chemically induced; D009154:Mutation; D010672:Phenytoin / Q000009:adverse effects; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D017422:Sequence Analysis, DNA; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: C493956:CDKN1A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; D010672:Phenytoin; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; D016283:Proto-Oncogene Proteins p21(ras)